Abstract: A real time billing system for accounts that locks out transaction events when the billing process is underway is provided. When a transaction event is received that should be posted to an account during the billing process, the account is locked. It is determined if the next bill time is in the past for the account and if it is, close billing of the account is performed on the account without billing the transaction event. After close billing of the account is finished, the transaction event may be posted to the account and the account unlocked.